Telephone-exchange system



'July 19,1927. 1,636,171

'E.H.CLARK a TELEPHONE EXCHANGE SYSTEM Filed Dec. 5, 1925 2 Sheets-Sheet 1 July 19, 1927.

- 1,636,171 E. H. CLARK TELEPHONE EXCHANGE SYSTEM fliled Dec 5, 1923 2 Sheets-Sheet 2 Patented July 19, 1927.

umren STATES PATENTOFFICE.

EDGAR H. CLARK, OF RICHMOND HILL, NEW YORK, ASSIGNOR TO WESTERN ELECTRIC COMPANY, INCORPORATED, OF NEW YORK, N. YL, A CORPORATION OF NEW YORK.

TELERHONE-EXCHANGE SYSTEM.

This invention relates to telephone exchange systems, and especially to such systems as employ automatic switchingappara tus in the" establishment of connections.

- The object of the invention isto secure a more flexible means of interconnecting telephone lines by an improved arrangement of circuits and controlling apparatus.

A feature of the invention relatesto a 1 switching. device for extending telephone lines, having a plurality of master control circuits each arranged to exercise a different control over said device, together with means for substitutingv one master control] circuit for the other without disabling the switchingpdevice.

By means of this arrangement an increase in the speed is secured inthe operation of, an automatic switch by a reduct1on in the' number of cooperating parts which function in. the selective movement of such a switch. This feature as will be readily seen, is of considerable importance where abnormal traflic conditions infrequently occur. Under these conditions the invention allows the use of a smaller number of selective switches tobe used than would otherwise be possible;v

Other features and advantages inherentin the invention will become apparent after aconsideration of the detailed description.

It has been chosen to illustrate the invention in connection with a line switch of the coordinate type-,such as is described in the United States patent of J. N. Reynolds, No- 1,507 ,140 issued September 2, 1924 and further .shownand described in United States patent to S. 13.. Williams, Jr.,- No. 1,517,331 issued December 2,1924. However, the invention is not limited in its application to this particulartype of switch as it may be applied to any selector switch which operates in conjunction with a controlling master circuit.

Referring to the drawing, Fig. 1 shows a number of subscribers" lines and also a portion of a master. control circuit consisting of a number of relays, which in their cooperation determine the selecting movements of the associated switch. at the same time preventing interference between. calling lines.

This will become apparent from the detailed description given hereinafter. In this figur are. also shown certain of the contacts of a key which is individual to the selective switch. The contacts of this key are shown in theinnormal or unoperated position. I

. Fig. 2 illustrates a line switch of the coordinate type, such as is described in the above mentioned i United States patents.

the master control circuit and the remaining contacts of thekey partly shown in Fig. 1.

Figs. land 2,. with Fig. 2to the right of Fig. lshow that. portion. of a telephone system which is sufficient for a complete understanding of the invention.

Subscribers lines 101, 102, etc. enter. the exchange and are multipled before vertical rows of contacts 201, 202, etc. in the line switch 200. Each calling line has access therefore'to the numberof horizontal links, as 217, 218, etc. ,These links are, divided into a. plurality of horizontal groups, of which two are. shown, 7 one; group including links 217, 218, another group including links 219, 220. There are as many of these groups of links as conditions require. Outgoing from the line switch 200 are a number of trunks 221, 222, each appearing before all the horizontal links. Every outgoing trunk is therefore accessible, to any calling subscribers line through a number of horizontal links.

, When a subscriber, as the subscriber at station 150, initiates a call, the vertical group relay 206 operates. This relay corresponds to that vparticlular vertical row of contacts before which the calling line appears- The operation: of relay 206 opens the starting circuit for all other calling lines in succeeding vertical groups, thus preventing two subscribers of lines in different vertical groups, for example, subscribers at stations 150 and 151, from. simultaneously operating a, plurality of vertical magnets, as

magnets 210 and 7 Relay 206 closes an operating circuit for relay 208 WlllCll locks in series with relay .109 which is common to all Fig. 2 also shows the remaining portion of I vertical groups. When relay 206' operates].

it opens at itsright'armature and back contact operating clrcuits for relays of other vertical groups similar to relay 208. Relay 208 also closes an operating circuit for the associated line vertical magnet 210, and closes a circuit to operate a horizontal group relay as relay 111, which in conjunction with relays as 112, 113, etc., controls the selection of an idle horizontal link. The time within which the calling line must be associated with an outgoing trunk is under the control of a pair of slow operating relays 110 and 115. Relay 115 begins to operate as soon as a line and a trunk vertical magnet, as 210 and 215, respectively, have been operated. Since relays 110 and 115 supply the operating ground for the horizontal magnets, as 211, 212, etc., they control the time within which the latter magnets must operate and complete connections through the switch 200.

It will be observed that when relays as 206 and 208 operate as a result of a subscriber initiating a call, no other subscriber, either in the same or a different group can cause the operation of line and trunk vertical magnets, until the first-mentioned subscribers line has been extended through switch 200. As soon, however, as this connection is completed the control circuit is released by the operation and release of relays 110 and 115 and a second subscribers line may now be extended through the switch.

From the foregoing general description it will, be apparent that no two calling lines "an be connected. to the same outgoing trunk since the master control circuit prevents two or lling lines from being associated with the same trunk through the same or through different horizontal links.

If. for any reason, however, it becomes necessary to disconnect the master control circuit without disrupting the operation of switch 200, an emergency key is thrown. The operation of this key results in the rendering ineffective of the master circuit and the substitution therefor of a common control circuit. It will be clear, therefore, that the operation of this key has a tendency to increase the possibility of interference between calling lines, during the time the master controlling equipment is temporarily out of service, but at the same time since the switch is controlled by a few fast operating relays, the functioning of such a switch is more speedy, thus allowing a greater number of connections to be completed in a given time than is possible with the use of the master control circuit.

An arrangement such as that shown in the drawing provides for greater flexibility since it combines the features of a non-interfering selective switch with a means for rendering such a switch more speedy in its operation when conditions demand.

For the purpose of illustrating the invention, a detailed description will be given first, of the manner in which a connection is completed under normal conditions, that is, with the emergency key unoperated; and second, of a connection completed with the same key operated.

Normal operation.

hen one of a group of subscribers, as the subscriber at station 150, removes his receiver,'the line relay 103 operates from battery through its winding, right outer armature and back contact of relay 104:, ring side of the calling line, through the calling subscriber-s loop to the tip side of the line, right inner arn'iature and back contact of relay 104 to ground through the low resistance relay 106 which operates. The operation of relay 103 closes a circuit for relay 206, which, together with relays 207 and 208 is individual to the particular vertical group of contacts 201 of switch 200, in which the calling line terminates. This circuit is as follows: battery, through the winding of relay 206, left armature and contact of relay 207, conductor 159, right hand contact 108 of the emergency key, right outer armature and front contact of relay 103, upper contact 105 of the emergency key to ground at the left armature and contact of relay 107. If a subscriber, whose line terminates in a different vertical group of contacts, as group 202, should now initiate a call, connection of his line through switch 200 would be blocked, since the operating circuit of the associated control relay 223 is opened at the right armature and back contact of relay 206. Relay 206 in. operating completes a circuit from battery, through the left winding of relay 208, right front contacts of relay 206, conductor 1-, to ground through the contacts of relays 109 and 110.

V hen relay 208 operates. it closes a locking circuit foritself from battery through the right hand winding thereof, right hand armature and front contact, conductor 152, winding of relay 109 to ground at the normal contacts of relay 110. Relay 109 operates in this circuit. The operation of relay 208 also closes a circuit for operating the associated vertical magnet 210 from ground at the normal contacts of relay 110, armature and front contact of relay 109, conductor 153, left middle armature and front contact of relay 208, right'hand contact 22 1 of the emergency key, to battery through the winding of magnet 210. The operation of magnet 210 prepares the contacts .in the vertical row 201.

Should a subscriber in another vertical group, as group 202. initiate a call at this stage, relay 228 will operate in a similar manner to that described for relay 206. However, since relay operates simultaneously with the operation of magnet 210,

magma it wil=l1 lock. to ground at the left armature: and; front contact of relay/22$ for purposes hereinafter described.

When'relay 208 operated, it also closed: a circuit for: relay 111 which; is common: to: the: group of horizontal linksincluding links 217,. 218, etc, asfollowsr from battery through. the right hand. winding of? relay 11 1,. right armature and back contact of re lazy 10?, upper contacts 128 off the emergencykey, right inner armature and. front con-- tact ofzrelay 103, right hand contacts 129' of the emergency key, conductor 155;. left; outer armature and front contact of relay 208,. left armature and contact of relay 1.17 to ground at the normal contacts 0t relay 110: The: operation of relay 1 11. opens at its. left armature and back contact the looking: circuit for other relays similar to relay- 1 11, thus preventing more than one: selec-- tion: of a horizontal. link being made at a; time. Relay 111 looks over a circuit traceable from battery, through the left hand;

winding, leftarmature and front contact of said relay, left armature and back contact of relay 116,. winding; of relay 117 to ground atthe normal contacts O'i relay 110. Relay 1:17 operates in this circuit and opens at its left armature and contact the locking cir-' cuit for; other relays similar to-relay"111",.thus preventing a plurality of calling lines from simultaneously gaining. access to the same outgoing trunk through: different horizontal links.

Assuming that trunkL222 is idle their the relay 225= associated therewith is-unoperated and vertical'magnet 215-will operate from battery, through its winding, lower arma' ture' and hack contact ofrela-y 225, right hand contacts 229 ofthe emergency key,.le'ft inner armature and front contact of relay 208,. conductor 153, to ground through the left armature and front contact'ot relay 109. Bela-y 225 does-not operate at this time" since its winding is shunted by the above traced ground. When magnet 215. operates, it prepares the vertical row of contacts 203,. and inconjunction with magnet 210 closes a circuit to operate one of the horizontal magnets, such as 212, which is associated with an. idle horizontal link. Assuming that link 218 is busy, the magnet 213v and relay 114 associated therewith are in an operated condition. It, therefore, the next link 217, is idle a circuit will be'closed from battery through the right hand winding of magnet 212, right armature and back contact of re lay 1-13, riglit armature and front contact of rclay 1'14, uppercontacts 1 19- of thexemergencykey, right hand armatureand front contact of relay 111, right hand armature a-nd'f'ront contact of relay 117', upper contacts 120 of the emergency key, conductor 156, middle armature and front contact of magnet 210, lowermost armature and front contact at magnet 21:5, conductor 157,: to? ground: at the; normal contacts-of relay 1211.

Attheftimethe circuit for operating hori'-- zonta'la magnet" 21 22 was closed, another" circuit was. established for: energizing the slow operating relay 115 tostartv the release: of theima'ster circuit; Thiscircuit is as follows :1

from ground at the middle armature and front contact of magneti215, lowermost arm-- ature anditront' contact of magnet 210,. cons duration-1 158, upper contact 122 of the emer-- its winding, sleeveconductor of the calling line-,cont'actsof switch 200 to the sleeve condiuctor of the outgoing trunk which is temporarily grounded by means of the lower middle contacts of magnet 21 5. When relays 110 and 115 finally operate subsequent to the operation of a. line vertical magnet and trunkv vertical magnet, the operating circuits for these latter magnets are broken.

The vertical magnets 210 and 21 5 therefore release. However, the connection through the switch is held by means of horizontal magnet 212 which is locked from battery through both: windings inseries, winding of relay1-1'3", contactsof switch 200 to thesleeve of the outgoing" trunk which is grounded in any well known manner.

4 When relays 110 and 1 15 have operated,

the holding circuits of Vertical control relay 208 and horizontal control relay 111 are broken and these relays release, in turn" releasing relays 1 09 and 117'. The release of relay 1T7 removes the short circuit from around the winding of relay 11 3, which operates in series with: horizontal magnet 212, thus rendering link 21'? non-select able by any other calling line. Relay 106' released asa resultof'the'operation of-cutofl relay 104. Relay 207 however, does not release" if a call in another vertical group had been initiated as'previously described, in which case relay 207 is locked to the left armatnreand front contact of a relay similar 7 to relay 206.

The operation of relays- 1'10 and. 115 also iornoved' the short circuit from around the winding of relay 225', which now operates from ground on thesleeve of the outgoing trunk, and renders trunk 222, busy to other oiflf rel'ay' 104: operates from battery, through j calling lines, All the relays of the master circuit are now released and in condition-to control the selection of another outgoing. trunk.

If, while the above" connection was in progress, a calling subscriber, whose line terminates in another vertical group as group 202, had initiated a call, the relay 228 associated therewith would be operated and relay 207 wouldremain locked, after the first calling line had been connected to an outgoing trunk, as previously described. This insures an cquable distribution of calls among the several vertical groups since in this case relay 206 cannot again operate until the call waiting in group 202 has been completed through switch From the foregoing description it will be apparent that no two calling subscribers can interfere with each other, since but one connection through the switch 200 is completed at a time.

Emergency operation.

Under certain conditions, however, it may be desirable to allow more than one calling line to make selection through the switch 200. This would be the case where abnormal traiiic conditions occur and a larger J number of connections must be made than when the switch is functioning normally. In some instances, it may be necessary to remove the master circuit either for repair or for other reasons. Ordinarily in such cases a second master circuit would have to be provided to take the place of the one disabled, thus necessitating the use of costly duplicate apparatus which would be idle for comparatively long intervals. The invention has for one of its purposes, therefore, to n'event disruption of service under emergency conditions by providing a common control circuit which is at once efficient, comparatively simple and speedy in operation.

For this purpose an emergency ltey is provided. hen a subscriber, as the subscriber at station 150, initiates a call and this key is operated, line relay 103 and relay 106 operate in the manner described under normal operation. The operation of relay 103 immediately closes a circuit for operating the particular vertical magnet, in this case, magnet 210 which is associated with the vertical row of contacts 201 in which the calling line appears. The circuit for this purpose is as follows, from battery, through the winding of magnet 210, left hand contact 221 of the emergency key, conductor 149, left hand contacts 108 of the emergency key, outer armature and front contact of relay 103, to ground at lower contact 105 of the emergency hey. When relay 106 operates a circuit is closed to actuate the vertical magnet 215 associated with an idle trunk. This circuit is traceable from battery through the winding of magnet 215, lower armature and back contact of relay 225, left contacts 229 of the emergency key, conductor 148 to ground at the armature of relay 106. It will be observed at this point that if a subscriber whose line terminates in another vertical group had simultaneously initiated a call, a

aniddle armature and front contact of magnet 215. While relay 125 is operating a circuit is closed to operate a horizontal magnet corresponding to an idle link. Assuming link 218 to be busy, a circuit is closed from ground at the normal contacts of relay 121, conductor 157, lowermost armature and front contact of magnet 215, middle armature and front contact of magnet 210, conductor 156, lower contacts 120 of the emergency key. left-hand contacts 129 of the en'iergency key, the inner armature and front contact of relay 103, lower contacts 128 and 119 of the emergency key, right-hand armature and front contact of relay 11 1, the armature and back contact of relay 113 to battery through the right-hand winding of magnet 212. After an interval when relay 121 operates a result of the operation of relay 125, the circuit for holding magnets 210 and 215 operated is broken and these latter magnets release, in turn, releasing relays 121 and 125.

The connection through the switch 200, however, is held. by means of horizontal magnet 212 which looks in series with the winding of relay 113 to the grounded sleeve conductor as described under normal operation. As soon as magnet 2'12 operates and locks, cutoff relay 124 operates, releasing relays 103 and 106. The release of relay 106 removes the short circuit frem around the winding of trunk relay 225 which now operates from the grounded sleeve conductor and renders trunk 222 non-selectable by other calling lines.

From the foregoing description it will be apparent that more than one connection can be completed simultaneously through switch 200, and since the number of relays which function in such connection is comparatively small, the speed with which connections are made is relatively fast.

What is claimed is:

1. In combination, a selective switch, a non-interfering master control circuit for controlling the operation of said selective switch, means for taking said. master circuit out of service, and means for automatically operating theswiteh thereafter without the use of any non-interfering master circuit- 2. In combination, a selective switch, a plurality of incoming lines, a pluralityof outgoing trunks, a non-interfering master circuit controlling the connection of said 1ncoming lines with said outgoing trunks, a

master circuit arranged to-simultaneously' control the extension of a plurality of connections through the switch, and manual means for replacing one of said master circuits by the other of said master circuits without disabling the switch.

3. In a switching device, a plurality of telephone lines, a plurality of connecting circuits, means for controlling the association of simultaneously calling lines with connecting circuits in a preferential order, and manual means for controlling the association of said simultaneously calling lines with connecting circuits in a non-preferential order.

4, In a switching device, a plurality of calling lines, a plurality of outgoing trunks, a plurality of connecting circuits, means for controlling the association one at a time of calling lines and connecting circuits, other controlling means, and manual means for causing said other controlling means to control simultaneously the association of a plurality of calling lines with connecting circuits. I

5. A switching device having vertical rows of contacts, lines appearing in certain of said vertical rows of contacts, trunks appearing in other of said vertical rows of contacts, circuits for extending said lines to said trunks, means for controlling the extension of simultaneously calling lines in a sequential order, other controlling means, and means for disabling said first mentioned controlling means to allow said simultaneously calling lines to be extended simultaneously under control of said second mentioned controlling means.

In witness whereof, I hereunto subscribe my name this 27th day of November A. D., 1923.

EDGAR 1-1. CLARK. 

